In the field of remote sensor networks, common applications include access control, perimeter alarm, vault alarm, and fire alarm systems. In each of these applications, it is necessary to have a central monitoring and relay unit, or control panel, to which was connected one or more dedicated sensors, usually in loop configurations. If any sensor was activated, then the central control panel carried out one or more specified routines such as activating an audible alarm and establishing a communications link with an appropriate central station if the sensor was in a perimeter alarm system. In such applications, it was also desirable to have one or more remote access modules which may permit a user to modify a subroutine. For example, a remote access module usually permitted the central control panel to bypass an alarm sequence subroutine if a certain troublesome sensor has been activated. In such instances, the remote access module may have be located outside a premises having a network of security type sensors. Upon entering an appropriate command, usually via a keypad, the module sent a predetermined signal to the central control panel based upon the command entered. In this manner, portions or the entire system could be enabled, disabled, or the system reset. Other types of access control modules were used to control access to restricted areas and to record the ID of the person entering that area.
For security type applications, remote access modules were usually in the form of numeric keypads. Early models were of a traditional 10 key configuration. A user, knowing a key combination, would enter the combination to activate a predetermined command instruction. Different combinations would permit the user, via the keypad, to execute different command instructions. As concern over the level of security provided by such models increased, more robust versions began to become available. An improvement included variable indica keypads used for access control applications wherein each key did not have a predetermined indica. Thus, an unauthorized observer could watch an authorized user's key stroke pattern, but because the values of the depressed key combinations would change at the next time of attempted access, knowledge of which keys were depressed in a particular order became meaningless without knowledge of what indica each key had at the time of observation. Several United States patents have been granted on such technology, including U.S. Pat. No. 4,333,090 issued to Hirsch and incorporated herein by reference.
In addition to security concerns, it was desirable to provide the user with information as to the status of the sensor network. To this end, several newer keypads provided textual information concerning the status of the system. Thus, a user could determine whether the system was armed, on standby, or had been compromised. Robust versions provided information concerning the status of any activated sensor loop and perhaps the location of any active sensor, but presented such information only by way of code. Because of the limited and cryptic nature of information provided by such units, a shortcoming of this technology has been the need for the user to know what certain displayed codes meant, and how to respond to them. As an illustration of this shortcoming, the following example is provided. In an alarm system having at least one such keypad, the alarm was activated and the user desired to know which area covered by the system has been affected, and also desired to deactivate the same and further, send a notice of false alarm to the public security agency. The user entered his or her access code via the keypad and might be able to observe information concerning the section of the system having the active sensor. This information was usually in the form of a sector location such as C-13. If the user knew the physical location of this sector and determined that it is likely a false alarm, then a deactivation code could be entered, if known and permitted. Furthermore, a cancel signal, which notified all destinations of the nature of the present status, may have be generated by further input. Nevertheless, each command must have been sequentially entered in the order proposed by the module's display.